Field of the Invention
The present inventions relates to a facsimile apparatus, a method of controlling a facsimile apparatus, and a storage medium.
Description of the Related Art
SLR (Send Loudness Rating) is known as an international standard for evaluation on a transmission level of a communication device (for example, a mobile telephone device). As a measure of the loudness of the transmit audio sent through a communication device microphone, for example, SLR compares the amplitude of the sound waves into the microphone to the resulting audio signal. The SLR comparison indicates a loss, and thus, when the transmission gain (amplification gain) of a facsimile is increased, the result is a reduction in the SLR.
In each country, a national standard for a transmission level in SLR is determined. For example, in China, there is an institution called Network Access License (NAL) that manages communication, and the standard GB/T15279-2002 for the transmission level has been established by China NAL. According to the standard, in a case where the distance to an exchanging system is large, the transmission gain is increased, while in a case where the distance to an exchanging system is small, the transmission gain is reduced. This is performed to prevent the sound/voice level from being too large or too small due to an influence of line impedance.
In conventional telephone devices, the distance to an exchanging system is determined based only on a line current in an off-hook state such that when the line current is smaller than a threshold value, it is determined that the distance to the exchanging system is large, but in a case where the line current is larger than the threshold value, it is determined that the distance to the exchanging system is small, and the transmission gain is determined based on the determined distance to the exchanging system.
Japanese Patent Laid-Open No. 2007-165967 discloses a technique in which an audio signal loss of a communication path is estimated, and the audio signal level is adjusted to a target value based on the estimated voice signal loss. More specifically, the telephone voice volume is adjusted depending on the line loss, of a communication path such that when the loss is large, the voice volume is increased to make it is possible for a user to easily hear a voice, but when the loss is small, the voice volume is reduced such that the voice is not too loud.
In a case where a facsimile apparatus has an internal telephone function, unlike a case where an external telephone device is connected to a facsimile apparatus, a telephone voice communication is performed via a silicon data access arrangement (SDAA, semiconductor NCU). To ensure the facsimile communication performance, the SDAA changes the impedance of the facsimile apparatus itself when necessary according to a DC-VI characteristic preset in the SDAA.
In the conventional technique in which telephone voice communication is performed without the SDAA intervening, the impedance of the apparatus is fixed and thus the current is stable. The current is proportional to the voltage, and thus it is allowed to determine the transmission gain based on the line current in the off-hook state so as to achieve a proper voice volume in telephone voice communication.
However, in the case of the facsimile apparatus configured to perform telephone voice communication via the SDAA, an influence of a change in internal impedance of the apparatus makes, it difficult to properly determine the distance to an exchanging system only based on the line current in the off-hook state.
Also in the technique disclosed in Japanese Patent Laid-Open No. 2007-165967, the technique does not take into consideration effects of a time-dependent change in impedance of the apparatus in the off-hook state.